Method and apparatus for operating wells



1931, E. P. HALLIBURTON METHOD AND'APPARATUS FOR OPERATING WELLS 2 Sheets-Sheet Filed Nov. 15, 1927 glwuv/nio a E. P. HALLHBURTQN METHOD AND APPARATUS FOR OPERATING WELLS Filed Nov. 15, 1927 2 Sheets-Sheet Patented Dec. 8, 1931 EBLE PALMER HALLIIBUBTON, LOS ANGELES, CALIIOBNIA METHOD AND APPARATUS F63 OPERATING WELLS Application fled November 15, 1927. Serial No. 288,348.

This invention relates to a method and apparatus for casin and operating wells, such as oil and gas we ls.

In the drillin of wells, such as oil and gas 6 wells, the well is frequently drilled through a number of spaced apart formations which will yield oil or gas. With the present apparatus and method for o crating and easing such wells extreme diificu ty is experienced in .10 producing oil or gas from more than one of such formations. Ordinarily in the operation of oil or gas wells the production of the well takes place only from the lowest formation which is encountered in drilling the well. In the operation of such wells, a string of casing is installed in the well leading from the surface of the well substantially to the formation from which gas or oil is to be produced. This casing is set at its lower end usually by a cementing process in order to seal the lower formation from communication with the upper formations so that water or other fluids from above can not migrate into the lower formation. This sealing and cementing of the casing at its lower end ordinarily requires that prior thereto mud fluid be circulated in the well and after the sealing operation this mud fluid is left around the casing which imposes a pressure upon all the upper formations preventing the fluids therein from entering the well bore around the installed casmg.

An object of the present invention is to provide a method and apparatus for operating wells by which it is rendered possible to produce fluids from two or more formations .encountered in the drilling of a well by means of a single casing installed in the well.

Another object of the present invention is to provide a method and apparatus for casing and handling wells by means of which the casing installed in the well may be opened at a desired point between the ends of the casing for establishing communication between the inside and exterior of said casing and also to provide a method and apparatus by which such opening may be closed when desired without sealing or otherwise effecting the formations on the exterior of the casing.

Another object ofthe present invention is to provide a method and a paratus for producing fluid from two di erent formatlons in a well without the pressure of the fluid of one formation being imposed upon the fluid from the other formation.

Frequently in drilling an oil well a producing sand, either gas or oil, is encountered but it is determined to drill the well deeper down to a lower oil or gas sand. When this is done ordinarily production can be had only from the lower oil or gas sand, the upper 011 or gas sand being closed off by the casing lowered to the lower formation. The hydrostatic pressure of the hydraulic fluid in the well is imposed upon the upper oil or gas bearing sand so that the oil or gas in such formations is prevented from rising to the surface of the well around the casing which is lowered to the lower formation. In accordance with the method and apparatus of the present invention, when the casing is installed at the lower formation and before production is made to take place from such lower formation, the casin is opened at a point opposite the upper 011 or gas bearing formation and the hydraulic fluid around the casing is drawn into the casing by a bailer or other means. In this way the hydraulic pressure'holding the oil or gas on the upper formation is removed and the oil or gas will rise around the casing. The method and apparatus of the present invention provide means by which this casing may be again closed without rescaling the upper formation and therby production may then be established through the casing from the lower formation so that product-ion takes place from both formations at the same time without necessarily the pressure upon either formation being imposed upon the other formation.

The method and apparatus of the present invention also. provide a means by which the large hydrostatic pressure on the oil string may be removed in cases of extremely deep wells so that an oil string of less strength than that which is ordinarily required may be employed. When a well is drilled by the rotary method to the depth of, for example 6,000 feet, the pressure of the hydraulic drilling fluid in the lower portions of the well is several thousand pounds or square inch. When the oil string is r st lowered into such a well, the hydraulic fluid 5 exists equally on the inside and outside of the string and does not tend to collapse the same. When, however, the string is-seated at its lower end and then bailed out to start production from the well, the pressure on the 10 lower end of the string due to the hydraulic fluid surrounding the string is very great. At present there is no satisfactory means by which the drilling fluid around the well string may be removed to eliminate or reduce 15 this pressure. By the process and apparatus of the present invention the well is operated so that the oil string may be opened up after the same is seated and this hydraulic fluid removed from the well bore all or in part by withdrawing the same through the inside of the oil string after which the oil string may be again closed.

The present invention also provides a means by which the entire exterior or a large portion of the exterior of a string of casing or oil string may be re-enforced with cement. By the methods now in use it is possible to force cement down through the. casing and up around the exterior of the casing to a height of about 2,000 feet. In wells of greater depth than 2,000 feet it is generally necessary to leave the exterior free from any re-enforcing cement. By the process and apparatus of the present invention the casing may be opened as desired at different points to force additional cement up around the exterior of the casing and accordingly the casing may be re-enforced with cement to any desired height up to as high as the surface of the well. 4

The present invention also provides a method and means, for operating wells whereby difi'erent fluids encountered in drilling the well may be made to assist one another in their elevation to the surface of the well. Frequently oil is found in the formation under insufficient pressure so that thesame will flow without pumping to the surface. By supplying additional gas in form of jets to the said oil, the same may be elevated to the well by the lifting action of the gas. The present invention provides a means by which, when both an oil and gas sand are encountered in the same well, the gas from the gas sand may be suitably introduced into the oil being withdrawn from the oil sand so that the gas operates as a means for assisting the elevation of such oil.

Various further objects and advantages of the present method and apparatus for casing and handling wells, such as oil wells will be understood from the description of a preferred form or example of a method and apparatus embodying the invention. For this purpose there is hereinafter described with reference to the accompanying drawings the preferred method and apparatus.

In the drawings Figure 1 represents an elevation in vertical section of an apparatus for casing or handling wells in place in a well hole;

F lgure 2 is an enlarged elevation in vertical section of a slip-joint and lateral valve employed in the present invention;

Figure 3 is a section on the line 3-3 of Figure 2;

Figure 4 is an elevation similar to Figure 1 with the apparatus in a different operating position; and

Figure 5 illustrates a modified form of the invention showing the apparatus in place in a well hole and mainly in vertical section.

Referring to the drawings,1 indicates a string of pipe or casing in place in a well hole, the string of pipe or casing 1 generally being referred to in the art as an oil string. Said string of pipe is connected with or includes a section of pipe 2 which is provided at its lowerend with a left hand external thread 3. Said thread is indicated as screwed into an internal left hand thread 4 provided by a swedge ni ple 5.. Said swedge nipple 5 is also a part of the oil string 1. The nipple 5 is indicated as provided with an extension the stop adapted to engage an external annu-- lar shoulder 8 on the pipe 2 for limiting the motion between the nipple 5 and the section of pipe 2 when the threads 3 and 4 are separated. The stop 7 and the shoulder 8 are indicated as preferably formed to provide a clutch face so that in the extended position of the parts 2 and 5 there is provided a clutch by means of which the pipe or casing below the nipple 5 may be rotated by rotation of the casing above the nipple 5 after the threads 3 and 4 have been separated. This permits a number of devices such as are shown in Figure 2 to be included in a single string of casing and each of such devices operated as re quired.

The extension 6 of the nipple 5 above the threads 3 and 4 is shown as preferably provided with a plurality of perforations or apertures '9 so that when the threads3 and 4c are separated and the pipe section 2 elevated relative to the nipple 5, fluid may be passed through such openings and thereby communication established between the interior and exterior of the casing 1 at a point opposite the nipple 5. The device comprising the section of easing 2 and swedge nipple 5 is thereby formed to operate both as a slip-joint clutch and as a lateral valve or means for opening the casing.

New referring to Figure 1 of the drawings, the apparatus is indicated positioned in order to carry out one preferred method of handling or operatin a well. The well bore is indicated as inclu ing an upper sand 10 below which there is a water sand 11 and below the water sand 11 is indicated a shale formation 12 on the top of a gas sand 13. Below the gas sand 13 is indicated another shale formation 14, then a water sand 15, a further shale formation 16 and finally an oil sand 17. Ordinarily in order to produce oil from the sand 17 it would be necessary to seal off the gas sand 13. This is for the reason that in order to protect the oil formation 17 from the water sand it is necessary to seat or seal 15 the lower end of the casing 1 in the bottom of the well, and it is also necessary that cement be forced around the exterior of the casing 1 up above the water sand 15 in order to prevent the water from such sand enterin the well 20 hole. The placing of the cement w ich is indicated at 18 around the lower end of the casing 1 and around the water sand 15 customarily requires that mud fluid first be pumped down the string 1 and up around the string in order to effectively remove from back of the string any obstructions which would prevent fluid cement pumped down casing 1 from I'lS- ing around the casing. This operation leaves the well hole both inside and outside ofthe 80 casing 1 filled with mud fluid. The cement is then placed in the casing 1 and forced down the casing excluding the fluid mud until it reaches the position indicated at 18. The well is then .held so that the cement will set in this position with the result that above the cement 18 around the casing 1 there is mud fluid which ordinarily extends to the top of the well. The pressure of such mud fluid upon the gas sand 13 is generally sufficient to 40 prevent the gas leaving said sand and producing around the casing 1.

When it is desired with the presentinvention to save the gas sand 13, there is set in the well, before the casing 1 is lowered, a

string of casing 19 down below the lower end of the upper water sand 11. This casing is then seated and cemented in place by cement as indicated at 20 to shut off the water sand 11 from the balance of the well bore. The

well bore is' then drilled through the remaining formations and the casing 1 lowered in place. The casing 1 as provided has inserted in it a lateral valve or slip-joint including the section of pipe 2 and swedge nipple 5 at a point in the casing 1 which will permit these parts to be disposed opposite the gas sand 13. During the lowering of the casing 1 the threads 3 and 4 are made up so that communication laterally through the casing 1 is cut off. The casing 1 is lowered into place so that its shoe 21 is at the top of the oil sand 17 and then the same is seated and sealed in place by means of cement. When the cement 18 has set so as to shut off the water sand 15, the upper section of the casing 1 is turned in a right hand direction which tends to tighten up all of the couplings in the casing except the threads 3 and 4 and serves to unscrew such threads so that the section of easing 2 may slide in the swedge nipple 5. After the threads 3 and 4 are unscrewed the upper part of the casing 1 is elevated thereby permitting communication through the side of the string and fluid mud passes from the interior to the exterior of the string or vice versa through the perforations 9. Figure 4 illustrates the apparatus in this position. A bailer may then be lowered into the string 1 and the casing or string 1 bailed out so as to draw away from the sands 13 the hydraulic fluid around the casing 1 above said sands. The gas formation 13 will thereby be relieved from pressure of fluid in the well and the gas from the formation 13 will be permitted to rise up around the string 1 between the casings 1 and 19 to the top of the well. After production from the gas sand is started in this way, the upper section of casing 1 may be again lowered and the casing rotated to again make up the threads 99 3 and 4. Thereby the interior of the casing 1 is effectively sealed ofl? from the sand coming from formation 13 while at the same time the closing of the casing has not prevented the free flow of gas from sand 13 up around the casing 1.

After the casing 1 is again closed the usual practice may be resorted to for establishing production from the oil sand 17 through the casing 1. drilling through the cement at the bottom of the casing and otherwise operating to open the production.

The object of having a left hand thread between the section of casing 2 and nipple 5 is obvious. It can be seen that all of the pipe in the string 1 which is coupled with conplings having right hand threads will be made up tighter when the pipe is turned in order to unscrew the left hand threads 3 and no 4. As a result there will be no danger of unscrewing the right hand threads in the string of pipe when the string is turned to the left for the purpose of again making up the left hand threads 3 and 4. It is obvious,

of course, that the device could be made having a right hand thread at 3 and 4 and operated by making up that thread or connection less tight than all of the other connections are made up. In certain cases the threads 3 tion assist fluid from another formation in 130 Such steps generally consist in 100 positively close the same when deits elevation from the well hole. The a paratus is illustrated in use in a well ho e in which there is an upper oil bearing formation 22 and a lower gas producing forma tion 24 with an intermediate water sand 23. The apparatus is shown as comprising a string of casing 28, the lower end of which is provided with a shoe 29 and the shoe 29 is indicated as set with cement 30 in the bottom of the well hole, the cement 30 being forced up around and above the water sand 23 so as to exclude the water from the sand 23 passing either upwardly into the oil sand 22 or downwardly into the gas sand 24-.

The casing 28 is indicated as including the valve shown in Figure 2 which provides a means for forming an opening in the side of the casing, the same including the swedge nipple 5 and the section of pipe 2 having left hand threads 3 and 4 adapted to be threaded together for locking the same in the closed position. The swedge nipple 5 is indicated as provided with a guide section 6 provided with apertures 9 for establishing communication between the interior and enterior of the string 28 when the threads 3 and 4% are separated.

Within the lower portion of the string of casing 28 there is positioned a section of pipe 25 extending down to the gas producing formation 24 and provided with a packer 27 engaging the inner wall of the lower portion of the string 28 below the valve so as to shut oil the oil sand 22 from communicating with the gas sand 24 around the casing 25.. The upper end of the casing 25 is indicated as terminating in a jet forming nozzle 26 at a point above the valve in the casing 28.

With the apparatus thus illustrated, the method of operating a well is as follows:

The casing 28 with the valve therein isfirst lowered into the well, the valve being positioned in the casing so that it will be located 'adiacen't the oil sand 22. The case ing 28 is then cemented in place to seal oil the water 2% and the lower portion of the weil bored out for establishing communication with the gas sand. The pipe 25 and its packer are lowered in position and the upper section of the casing 28 is turned to theleit to break the threads 3" and 4 and permit the oil from the formation 22 to enter the casing 28. As the oil enters the casing 28 through the perforations 9 and passes up around the nozzle 26, the gas passing from formation 2% is injected into the oil thereby assisting the elevation of said oil to the surface of the well. By injecting the gas from the formation 24; into the casing 28 in the form of an upwardly directed jet, the pressure of the gas in formation 24; is not applied to the oil bearing formation 22 but such pressure in place produces a suction in the casing 28 tending to draw in the oil from the formation 22. In this manner the the string whereby two method and apparatus of the present invention provide a means by which production from two different formations may take place simultaneously and provide also a means by which the fluid from one formation assists the production of fluid from another formation.

While the method and apparatus for handling wells herein described are well adapted to carry out the objects of the invention, it is understood that. various modifications and changes may be made without departing from the invention and the invention includes all such modifications and changes as come within the scope of the appended claims.

l claim:

1. A method of operating a well comprising, lowering a string of casing into the well, cementing the lower end of the string of casing to close oil the formation below the strin from the space around the string, establis ing communication between the space around the string above the cement seal and the inner bore of the casing in order to permit mud fluid to drain into the string, interrupting such communicationafter the mud fluid has drained into the casing, drilling out the cement at the bottom of the well hole to establish communication through the lower end of the string, and thereafter again establishing communication between the space around the string above the cement seal and the inner bore of the string, whereby two producing strata may produce into one string.

2. A method of operating a well which comprises, lowering a string of easing into the well, cementing the lower end of the string to close ofi the formation below the string from the space around the string and to temporarily close the lower end of the string, establishing communication between the space around the string above the cement seal and the inner bore of the casing in order to permit mud fluid around the string to pass into the string, interrupting such communication after the fluid has drained into the casing, drilling out the cement at the bottom of the well hole to establish communication through the lower end of the string, and thereafter again establishing communication between the space around the string above the cement seal and the inner bore of producing strata may produce into one string.

3. A method of producing fluids from two spaced apart formations encountered in drilling a well which comprises, lowering into the well a string of casing to the lowered formation, cementing the lower end of the string to close oi? the formation below the string from the space around the string, establishing communication between the space around the string and interior of the string until mud fluid around the string has drained into the string and the upper formation is in condition to drain oil into the string, then interrupting communication between the space around the string and the interior of the string, drilling out the cement at the bottom of the well hole to establish communication through the lower end of the string and the lower productive formation, thereafter again establishing communication between the space around the string above the cement seal and the'inner bore ofthe string whereby two producing strata may produce into one string.

Signed at Los Angeles, Calif., this 9th day of November, 1927.

ERLE PALMER HALLIBURTON. 

